Key switch mounting



June 12, 1951 M. J. LARSEN 2,557,034

KEY SWITCH MOUNTING Filed Oct. 14 1949 2 Sheets-Sheet 1 June 12, 1951 JLARSEN Q 2,557,034

KEY SWITCH MOUNTING Filed Oct. 14, 1949 2 Sheets-Sheet 2 Merit z}? Z a2: e z/ Patented June 12, 1951 KEY SWITCH MOUNTING Merwin J. Larsen,Villa Park, Ill., assignor, by

mesne assignments, to Central Commercial Industries, Inc., DelawareChicago, 111., a corporation of Application October 14, 1949, Serial No.121,335

6 Claims. 1

This invention relates to switch mounting means and has particularreference to means designed, constructed and adapted primarily for usewith a piano or other keyboard musical instrument for detachablymounting a gang or assembly of electric switches upon the case of thepiano in a manner to operatively relate actuators of the switches withrespective playing-keys of the instruments keyboard and whereby whenplaying said keys the switches will be operated, i. e. they will be offwhen the keys are raised and on when the keys are depressed.

A device of the character above set forth is particularly useful incombination with the type of electronic musical instrument disclosed inU. S. Letters Patent No. 2,250,065 of July 22, 1941, in which devicemeans are employed for producing audio signals having the tonefrequencies of notes associated with diiferent playingkeys of thekeyboard of a piano or other keyboard musical instrument. In saidinstrument, assigned playing-keys are coactive with electric switcheswhich are connected in an electrical network and with tone frequencygenerators and a translating device, whereby sustained tones can beplayed from said keyboard as and when desired. a

An instrument of the class disclosed in said Patent No. 2,250,065 hasbeen found to be very useful if and when used with a keying mechanismcapable of being readily attached to and removed from a piano so thatthe mechanism can be removed from a piano situated at one place andapplied to a piano situated at another place such as when a travelingband, orchestra or a performer finds it costly and inconvenient totransport a piano from place to place.

An essential object of the invention is the provision of a simple,compact and inexpensive mechanism which enables an assembly of electricswitches to be readily applied to or removed from any standard pianowithout requiring any structural alterations in the instrument.

Another object is the provision of a mechanism, the form, constructionand design of which enable quick and convenient adjustment of themechanism that insures a necessary coactive relation of the keys of thepiano to the actuators of the respective electric switches.

A further object is the provision of a mechanism which, when adjusted toa piano as intended will not be subject to accidental derangement whenin use.

A mechanism for attaining the above mentioned objects and others isdisclosed in the accompanying drawings, in which:

Figure 1 is a view in front elevation of a piano showing the inventionapplied;

Figure 2 is a sectional perspective view of one embodiment of myinvention;

Figure 3 is a view in front elevation of a portion of a piano showingthe invention applied, the parts being shown on an enlarged scale;

Figure 4 is a perspective view of one of the supporting brackets;

Figure 5 is a sectional perspective view of a further embodiment of myinvention;

Figure 6 is a view partly in elevation and partly in section of a stillfurther embodiment of my invention; and

Figure 7 is a section of a portion of the U- channel bar showing one ofthe electric switches, the line XX indicating the plane of a playingkeywhen the switch is in an 01f position.

In carrying the invention into practice and on referring to Figures 1-4,inclusive of the accompanying drawings, the device consists of alongitudinally disposed U-bar In of sheet steel, aluminum or othersuitable material, including Bakelite, the same providing a mounting fora plurality of longitudinally spaced apart electric switches l I, eachhaving a dependin actuator l 2 consisting of a vertically slidable pin,the lower end of which presses lightly against a preassigned playing-keyK of the keyboard of a piano P or other keyboard musical instrument.While these switches may be of any approved well known construction, itis preferred that they conform to the constructional features of theswitch disclosed in the patent to M. J. Larsen, et al., No. 2,487,977 ofNovember 15, 1949. Mounted in the channel of said U-bar It! are spacedapart busbars I3 and 14, the former of which is grounded at [5. Each ofsaid electric switches comprises a resilient element of conductivematerial such as springy wire formed with a long coil l 5 functioning asa retractile spring and a short angularly disposed coil ll functioningas a contactor and positioned so as to alternately engage and disengagethe bus-bars l3 and M in response to vertical motion of a playing-keywhen the piano is played. At the juncture of the short coil IT with thelong coil iii, the wire of which the coils are formed is attached to avertically travelling follow nut I60, of electrical insulating materialin which nut, the actuator I2 is threaded for vertical adjustment. Thelower end of the long coil I6 is attached to a signal input terminal I8whereby the actuator is lightly urged in a downward direction so thatits lower end rests upon the upper surface of the playing-key at theback end thereof and whereby, as the actuator lowers upon depressing thekey, the short coil ll will shift from a position of engagement with thegrounded bus-bar !3 to a position of engagement with bus-bar M fortransmission of a tone signal to an audio amplifier (not shown).

The switch assembly is herein shown as applicable to an eighty-eightnote piano. For the purpose of the invention, the switch may consist ofi2 any desired number of individual electric switches. in the instantembodiment of the invention,'sixty individual switches are employed. TheU-bar IE! is slightly shorter than the length of the keyboard, and, asshown, the upper and lower flanges Illa and [b of the bar are eachformed with a longitudinal slot 20. At each end of the bar is a bracket2|, shown in detail at Figures 2, 3 and 4. As the brackets aresubstantially identical, a description of one will sufiice for theother. Each of said brackets consists of a metal stamping formed with ,avertical arm 22 which extends through the vertically alined slots 20 sothat the bar It may be shifted horizontally when applying the device tothe piano. The bracket has a horizontal flange 23, on which flange Iilbof bar it rests. The bracket is then bent downwardly at 24 andterminates in a fiat, horizontally disposed lug 25.

When attaching the device to the keyboard of the piano, the bar Ill isplaced in a horizontal position at the front of the stop rail R. Thebrackets 2! are then adjusted to aline their lugs 25 with the respectiveend playing-keys. Removable wedges 25 are then inserted between theupper surfaces of the keys at the back ends thereof and the undersurfaces of lugs 25, the latter being positioned beneath rail R, so asto be forced in secure engagement therewith when attaching the wedges,as aforementioned. Thus applied, the actuators are operatively relatedto their respective playing-keys and the entire key assembly maintainedin a rigid position where it cannot be easily deranged. In this form ofmy invention, application of the wedges as above stated forces the frontends of the end keys down so that they are rigidly secured in'thesepositions. These two keys are, therefore, rendered inactive and cannotbe played. g

The lugs 25 are each formed with an elongated slot 25a and, as shown inthe embodiment at Figure 5, the slot receives a screw 2% which is driveninto the stop rail R from the bottom thereof. In this embodiment, theend keys of the piano keyboard arefree to be employed.

In the embodiment shown at Figure '6, the lug 25 receives a screw 28which is driven downwardly into the key K at a point beneath the stoprail R. A spacer t is associated with the key guide pin 271a to stopmotion of the key in a downward direction as in the first describedembodiment of my invention. I

While the-modifications of the invention disclosed at Figures 5 and '6require disassembling parts of the piano case in order to effectapplication of the device to the piano, there are instances where one orthe other of these embodiments may be preferred. In each of thesemodifications, the key switch rail may be rigidly supported in ahorizontal position Where the lower end of the pin I2 of each separateswitch is prop erly correlated to its respective playing-key. After thebar It has been rigidly mounted on the piano, the pins 12 may beadjusted vertically so that their lower ends rest lightly upon theplaying-keys by action of the coil IS.

The bar has a removable cover plate 29. When the device is applied asshown at Figure 1, the cabling C from the signal generating and signaltranslating mechanism M may be run from the switches so that themechanism may be placed at one end of the piano and supported by thefloor. p

In each of the several embodimentsof my invention, the vertical arm 22of the bracket is.

4 formed with a threaded hole 30 to receive a clamp screw 3|. After thebrackets have been firmly secured in their intended positions and thebar If] has been adjusted to aline the pins I2 of switches II with theirrespective playing-keys,

, the screws are turned so as to establish a secure binding engagementwith the inner face of the vertical wall of said channel bar, therebysecuring said bar against longitudinal movement.

Either one of the several disclosed embodiments represents a simple,compact, neat appearing device for effecting quick and convenientapplication of the switch assembly to or removal of same from the pianoas and when desired.

It is, of course, understood that the brackets 2! are formed as rightsand lefts and that except for this they are structurally the same. Onlyone of the complete key operated switches is shown but as they areidentical, it sufiices to say that when mounted on rail ID inprecalculated spaced relation to each other, the pins I2 are disposed sothat for each black key and for each White key in the musical range ofthe device, they will be coactive with a respective one of said pins.

What I claim as my invention is:

1. An electric switch assembly for use with a keyboard musicalinstrument, said assemblycomprising a longitudinal series of electricswitches,

a horizontally disposed rigid bar overlying said keyboard and disposedparallel thereto and on which said switches are mounted, each of saidswitches having an actuator adapted to be operated by a respectiveplaying-key of said keyboard, supporting brackets for said bar, each ofsaid brackets having 'a horizontally disposed lug insertable between arespective playingkey and a fixed part of said instrument, and means forand coactive with the lug of each separate bracket for securing same ina fixed position on said instrument to thereby retain said bar againstmovement relative to said keyboard.

2. An electric switch assembly according to claim 1, wherein said bar isadjustable vertically on said brackets.

3. An electric switch assembly according to claim 1, wherein said bar isadjustable vertically and horizontally on said brackets.

4. An electric switch assembly according to claim 1, wherein saidsecuring means comprises wedges which are coactive with the lugs of therespective brackets and with the respective playing-keys with which saidlugs are associated for forcing said lugs in clamped engagement with afixed part of said instrument.

5. An electric switch assembly according to claim I, wherein saidsecuring means includes a fastening device for and c'o'active with thelug of each separate bracket and engageable with a fixed part of saidinstrument.

6. An electric switch assembly according toclaim 1, wherein saidsecuring means includes a fastening device for and coactive with the lugof each separate bracket and engageable with the respective playing-keywith which said lug is associated.

MERWIN J. LARSEN.

REFERENCES CITED The following references are of record in the KoehlJuly 22, 1941

